This invention relates generally to voltage regulating systems and specifically to voltage regulating systems for integrated circuits where the maximum power the circuit must dissipate is of prime importance.
Regulators may be broadly characterized into series and shunt types. Generally, a series regulator is, as its name implies, connected in series between a source of unregulated voltage and a load and functions to maintain a constant voltage at the load. Ideally, the impedance presented by the series regulator, at its maximum regulation point (saturation) is zero and, consequently, its internal power dissipation is minimum at this point. The series regulator may include a shunting resistance through which portions of the load current pass depending upon the state of the regulator.
A shunt regulator regulates by diverting current from the load in the event of increased supply voltages. The power consumed by a shunt regulator is negligible below the potential at which it regulates and increases in a linear manner with increases in supply voltage. The shunt regulator also includes a resistance connecting it to the source of unregulated potential and the load is connected to the junction point. This resistor and the shunting resistor in the series regulator dissipate power, which while always undesirable, is especially so in integrated circuit applications.
It would thus be very desirable to arrange a regulator such that its maximum internal power dissipation, over the regulating range, is minimized and such that only the regulator components themselves (as distinct from the voltage dropping resistors) are actually in the integrated circuit. The latter condition involves the important economic consideration of maintaining a reasonable number of pin connections between the integrated circuit (IC) and external circuitry, which, as is well-known, constitutes a major cost of an IC.
Accordingly, a principal object of this invention is to provide a novel regulating system.
Another object of this invention is to provide a regulating system having minimum regulator power dissipation for a given set of regulating criteria.